Trapattoni to miss Argentina friendly
In a statement, the FAI said Trapattoni had abdominal pain which turned out to be from minor scar tissue from previous surgery. It later said said he had a "successful and straightforward minor surgical procedure performed."
"He is now in recovery... and it is anticipated he will remain in hospital to recover over the weekend," the FAI added.
Assistant manager Marco Tardelli will take charge of the Irish squad when it meets Argentina in Dublin later on Wednesday.
Trapattoni was kept overnight in hospital after suffering from nausea since Sunday, which the 71-year-old Italian thought may have been caused by shellfish he ate.